Function parseOptional

test/fixtures/snapshot/typescript.js:32258–32264

(t)

            }
        }
        function parseOptional(t) {
            if (token() === t) {
                nextToken();
                return true;
            }
            return false;
        }
        function parseOptionalToken(t) {
            if (token() === t) {
                return parseTokenNode();